DEPARTMENT OF MECHATRONICS ENGINEERING
MECHATRONICS ENGINEERING LAB V (MCT 4239)
* 4 : CONTROL LOOP EXPERIMENTS
The following list of experiments are closed loop experiments that are specified for tuning and P,I, D studies.
* Experiment 4.1: EFFECT OF P, I and D on process Plant
- To familiarize with the Tuning Panel of the DCS
- To capture Trending on the DCS
- To understand the effect of Proportional (P), Integral (I) and Derivative (D) to the setpoint change or load disturbance
1) Set the Setpoint on the DCS to 50%. Record the PV value it should be near the 50% mark. Now set the DCS Controller faceplate to ‘Auto’ and let it stabilize.Make sure the discharge valve on plant is fully opened.
2) Set P = 30 , I = 3, D = 3 as initial values of PID.
3) When stabilize Change the P Value , while maintaining the I and D Values. Note the responses by disturbing the setpoint up or down about 5%.
4) Save the trend values at the DCS. Comment on the effect of P to a disturbance.
5) Stabilize the Process at the 50 % mark and leave it at ‘Automatic’ control. Now change the I values , while maintaining the P and D Values. Note the responses by disturbing the setpoint up or down about 5
6) Save the trend values at the DCS. Comment on the effect of I to a disturbance.
7) Stabilize the Process at the 50 % mark and leave it at ‘Automatic’ control. Now change the d values , while maintaining the P and i Values. Note the responses by disturbing the setpoint up or down about 5%.
8) Save the trend values at the DCS. Comment on the effect of D to a disturbance . Use D=1 , D=10
9) Record the Results in the table 7 below
TABLE 7: Effects of P, I and D action on the process
Item| Description| Results|
1| Increasing P| |
2| Decreasing P| |
3| Increasing I| |
4| Decreasing I| |
5| Increasing D| |
6| Decreasing D| |
* Experiment 4.2: PROCESS REACTION CURVE METHOD
- To familiarize and operate a level Control Experimental Rig. - To control the level of water in the tank manually.
- To investigate the process reaction curve method of tuning for open loop.
1) Set the TUNING PANEL OR TREND on the DCS to the largest time scale to compress the graph for easy viewing of graph. Do not use the expanded scale.
2) Select ‘DCS’ at the plant and operate the pump P01 at the local panel , by pressing the start button for P01.Ensure that MV is set at 50 % from the DCS. Fill up tank T02 with water until its level reaches about 50% of the level..
3) Adjust the Discharge Valve V-11 until the water level stabilizes at the 50% mark. At the DCS . move the MV value by 2% and observe the step response of the plant. Ensure that there is no over spillage at tank T-02. Allow the level to find new steady state level.
4) Capture the trend at the DCS and print out a copy to measure the deadtime , Time Constant and Process Gain Values. Refer to table 5 to compute the initial estimate of the P, I and D values and tabulate the new values in table 8.. Draw the curve in figure 5
5) These may not still be the final values, try to manually improve the curve by adjusting minor changes to the initial estimates. To check the response , do a small step change ( DCS SV value) or load change ( Valve V-11). Plot the best process curve in figure 6
NOTE : IF DELAY CAN NOT BE MEASURED ON SCALE. YOU CAN USE THE SAMPLING SPEED OF DCS OR ELECTRONIC VALVE DELAY AS A GUIDE eg DEADTIME IS 50mS/ 100ms
Dead Time ,L= sec, Time Constant, T= = sec Fig 5:...